A golf ball has a large number of dimples on its surface. The dimples disturb airflow around the golf ball during flight and cause turbulent separation. This phenomenon is referred to as “turbulence”. Turbulence causes a separation point of air from the golf ball to shift rearward, and thus drag is reduced. Moreover, turbulence promotes the displacement between an upper separation point and a lower separation point due to backspin, and thus lift acting on the golf ball is enhanced. Accordingly, good dimples disturb airflow better, and thus largely extend the flight-distance.